My choice would be the Nissan Skyline GT-R R32, R33, R34...it's a shame it was never officially imported to the US.

As far as current cars, there are several models from the Alfa range I'd love to see here--the sedans, the Brera coupe and new Spyder, the GT coupe.. the Opel Astra and Vectra, the TVRs...maybe some Peugeots...